Hydroponic plant culturing requires the concentration of nutrients in the supplied solution to be maintained at a constant level. For example, phosphate ion concentration directly affects crop growth, which necessitates the development of convenient and rapid techniques for on-site phosphate quantitation. Herein, we developed a new low-cost colorimetric method of quick on-site phosphate quantitation based on a modification of the conventional molybdenum colorimetric method. Specifically, the nutrient solution treated with ascorbic acid and molybdate was analyzed by colorimetric method after 10 min incubation, and a phosphate quantitation protocol was proposed. To verify this protocol, 50 nutrient solution samples with concentrations of 0–200 ppm were used to develop a model and perform a validation experiment, and the PLSR (Partial Least Squares Regression) and PCR (Principal Component Regression) models were developed and validated using a crossvalidation method and sample transmission spectra. The PLSR model, employing smoothing preprocessing at a 5 nm wavelength spacing, exhibited the best prediction performance and showed an error of ~10% within the measurement range during verification. In addition, an artificial neural network-based model achieved for the training set and for the validation set. Finally, we developed convenient-to-use software for phosphate ion quantitation by the presented method and performed a demonstration test.

中文翻译：

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基于光谱分析的便携式传感器在水培溶液中磷酸盐定量的应用

水培植物培养要求所提供溶液中养分的浓度保持恒定。例如，磷酸根离子的浓度直接影响农作物的生长，这就需要开发方便快捷的现场磷酸定量技术。在此，我们基于对传统钼比色法的改进，开发了一种新型的低成本比色法，用于快速现场磷酸盐定量。具体来说，孵育10分钟后用比色法分析抗坏血酸和钼酸盐处理的营养液，并提出了磷酸盐定量方案。为了验证该方案，使用了50种浓度为0–200 ppm的营养液样品来建立模型并进行验证实验，使用交叉验证方法和样品透射光谱，开发并验证了PLSR（偏最小二乘回归）和PCR（主成分回归）模型。PLSR模型采用在5 nm波长间隔处的平滑预处理，表现出最佳的预测性能，并且在验证过程中在测量范围内显示约10％的误差。此外，实现了基于人工神经网络的模型 用于训练集和 验证集。最后，我们通过提出的方法开发了用于磷酸根离子定量的易于使用的软件，并进行了演示测试。